Known methods of galvanic isolation used in on-chip or in-package digital signal processing (DSP) systems include optoelectronic-couplers, inductive coupling transformers, capacitive couplers, inductive coupling bond wire transformers, and inductive coupling magnetoresistor-based coupling devices.
FIG. 1 shows a galvanic isolation system 100 that utilizes an optoelectronic coupler. The system 100 comprises proven technology that is widely used and provides low cost per basic unit. The system 100 provides high isolation capability and requires no data encoding. However, it requires high power (10 mA). If fast light emitting diodes (LEDs) are used, they are expensive and their response time degrades over time. The system 100 also exhibits low speed performance (−50 Mbps), high temperature dependence and utilizes a large board footprint.
FIG. 2 shows a galvanic isolation system 200 that utilizes an inductive coupling transformer. The system 200 is low cost, exhibits high performance and can be implemented in CMOS technology. It also exhibits high common mode rejection, utilizes very low power, depends little on temperature and utilizes a small board footprint. However, it is sensitive to external magnetic fields and requires clock encoded data.
FIG. 3 shows a galvanic isolation system 300 that utilizes capacitive coupling. The system 300 is low cost and can be implemented using CMOS technology. It exhibits little temperature dependency and is relatively immune to magnetic interference. However, it also exhibits low common mode transient immunity, higher noise, larger area than the other conventional options, and requires clock encoded data.
FIG. 4 shows a galvanic isolation system 400 that utilizes an inductive coupling bond wire transformer. The system 400 exhibits poor flux coupling, low speed and poor manufacturability.
FIG. 5 shows a galvanic isolation system 500 that utilizes an inductive coupling magnetoresistor. The system 500 exhibits benefits similar to and the same data rates as the transformer systems. However, it requires giant magnetoresistor (GMR) technology and is sensitive to external magnetic fields.